Different Photo Voltaic systems with their advantages:

Sizing a solar system

How Does Solar Electricity Work?

About Batteries

What is a battery? A container consisting of one or more cells, in which chemical energy is converted into electricity and used as a source of power. This chemical reaction creates a flow of electrons in a circuit. All batteries are made up of three basic components: an anode (the negative side), a cathode (the positive side), and some kind of electrolyte (a substance that chemically reacts with the anode and cathode). A battery stores energy to be used at a later stage thus providing access to instant energy on demand. The anode, cathode & separator thickness determines the number of cycles and lifetime expectancy of the battery.

What does a battery do? A battery is a device that is able to store electrical energy in the form of chemical energy and convert that energy into electricity. The electrons and ions flow because of the chemical reactions happening inside the battery, usually two of them going on simultaneously. The exact reactions depend on the materials from which the electrodes and electrolyte are made.

There are different types of batteries for different applications!

Batteries come in all different shapes, sizes, voltages, and capacities i.e. amount energy stored. Batteries can be made with all sorts of different chemical electrolytes and electrodes. There are really two type’s namely primary batteries that are ordinary, disposable ones that can't normally be recharged. Whereas secondary batteries can be recharged. The three main kinds of primary batteries are zinc carbon, alkaline and lithium. They are often referred to as dry cells because there is no liquid in them. The most common rechargeable batteries are lead-acid used in cars that are not suitable for solar applications. Lithium-ion batteries are the fastest-growing type of rechargeable batteries and are in your cell phone, laptop, etc. and now solar battery applications. The downside to this technology it is in its infancy stage thus making it relatively expensive.

What type of battery do I need?

It’s critical to understand that your solar battery end use will determine the type of solar deep cycle battery you require. For example, if you operate a photovoltaic system where the solar battery is only used for backup, as one would with a Multi-Hybrid System, then one should look at a high-quality standby deep cycle battery. If you will be using your solar batteries every day to power your home, office, workshop or farm/lodge, as you would in an Island System, then you need to consider a high-quality active cycling deep cycle battery that is up to the challenge.

Discharge Rates

If a battery discharges faster or slower, the battery will deliver more or less energy respectively. The discharge standard is adopted worldwide and given the abbreviation “C”. In solar we generally have 12 hour days, thus we should use the C12 or C10 rating.

Most battery datasheets will give you a table of Amp hours vs discharge time (C-rate).

Make sure the battery capacity being used is rated at C10 or C12 for solar applications.

Remember to factor in Depth of Discharge for your battery. Batteries age due to discharging and recharging. The number of cycles depends on the depth of discharge, as shown in the graph below.

Battery Degradation

Battery cycle life has a linear degradation. That means that if a battery has completed 50% of its cycles it will only be able to store 50% of its capacity. This is important for people that want to be off-grid to ensure one has a bigger enough battery bank. This is one of the most important reasons why a battery bank should be sized for three days autonomy.

Battery monitoring

The essential function of a battery monitor is to calculate ampere-hours consumed and the state of charge of a battery. Ampere-hours consumed is calculated by integrating the current flowing in or out of the battery. In the case of a constant current, this integration is equivalent to current multiplied by time. A discharge current of 10A during 2 hours, for example, amounts to 20Ah consumed. All our battery monitors are based on a powerful microprocessor, programmed with the algorithms needed for precision monitoring. Standard information like; battery voltage (V); battery charge/discharge current (A); amp hours consumed (Ah); the state of charge (%); all the information is accessible via the on-line portal and warning email is programmable.

Can I afford to buy a cheap deep cycle battery or solar battery?

The answer is obviously NO! Never buy on price alone. Energy storage is the key to the long-term sustainable performance of your solar power system. Low-quality batteries are also one of the key reasons for solar power system failure, so be aware of what you are buying!

The real cost is not the selling price of a solar battery.

How do I assess the REAL cost of a solar battery?

Here is how you do it: The REAL cost of a deep cycle battery is determined by its cost of purchase (selling price) and its subsequent service life. Battery service life is determined by two factors, namely the number of cycles and temperature degradation due to time passing or standby life. The selling price is divided by the number of cycles (taking into consideration depth of charge). Therefore the cost per Kilowatt the battery produces is what your real cost actually is.

How do you know what is the correct battery to buy?

Simply ask the battery salesperson three most important questions namely;

How many deep cycles will this battery obtain?

What is the standby life of this battery?

What is the warranty period?

The end use application will determine the size and type of battery required. The size of the battery bank can be calculated by the total Amp hours required by the battery bank. From these calculations with the Real Cost of a battery will make the decision-making process quite simple.

At Solartech West Coast we will size your battery bank and advise you on the best options. We only sell battery brands that we are confident that will serve your solar system effectively and efficiently.

Panel position

How do I know where to position solar panels on my roof?

The amount of solar energy that the earth receives on a daily basis is far more than the total energy than what we need – as a matter of fact – almost 6 000 times more. The sun is a powerful source of energy. The picture below indicates the size of the sun compared to earth, what more do we need to say about this source of power for our earth?

Southern Africa is swathed in a solar resource easily available and is perhaps the highest in the world enjoying sunshine almost all year round. Thus providing South Africa with excellent radiation for renewable energy. The solar radiance levels, particularly those in the Northern Cape and the North-West Province are exceptional, which means that the strength of the solar power received in South Africa is phenomenal compared to other counties in the Northern Hemisphere.

Needless to say South Africa is geographically well-placed to make use of this free and reliable source of energy which the sun has to offer day in and day out.

This leads one to the question:

How do I know where to place solar panels [modules] on my roof?

South Africa is in the Southern Hemisphere. Therefore True North is the most efficient direction solar panels must face to obtain the best all year round optimum radiation from the sun. The sun is higher in the sky in summer, almost directly above as can be seen from the diagram below.

Where as in winter the sun is at a lower angle as can be seen from this diagram.

So the big question is: “What do you do if you don’t have a North facing Roof?” If you have a South facing roof unfortunately a roof option won’t work. Don’t despair we can look at a ground mounting solution. Solar Carports serve the dual function of creating shade for vehicles in a parking area and simultaneously providing an area for the solar modules to be mounted upon.

On farms or when there is open space, a ground mounted solution will eliminate the incorrect roof orientation. The examples below are some of the solutions we offer our clients.

Another option is an East/West orientation. In Cape Town, during summer we have early sunrises at 6.00 am and late sunsets at 8.00 pm which are great but in winter it will be less efficient.

From the graph below one can see although East/West is efficient in summer overall a true North is actually the most efficient orientation for a solar module in the Sothern Hemisphere.

Therefore when you purchase a new home ensure the roof orientation is true north and there is sufficient roof space, approximately 20 m² should be sufficient for most solar systems.

How do I know if my roof structure is strong enough for the weight of solar modules?

If your rafters are at a maximum of 1 meter apart and the structural integrity of the roof design is solid. Our installers will immediately on site be able to ascertain if a residential home roof is strong enough to hold the weight from a solar array.

The local municipalities do not require any plans for the solar panels to be installed on a roof, provided they are installed directly onto the roof without infringing on any height restrictions.

Business Owners what you need to negotiate prior to signing that lease contract.

Business owners before you sign a lease include in writing from the future landlord that permission will be granted to install solar panels on their roof. Also ensure a structural engineer approves the roof structure to be able to withhold 20 kilograms per 1,5 meters squared. This will give you the knowledge upfront to know if solar panels can be installed on the roof.

Grid Tie

Typically, grid connected PV systems are utilized purely for energy cost reduction and self-consumption of green power. Unutilised power generated by the Solartech West Coast PV Grid-Tie system may be fed back into the utility network.

This avoids green power being lost as may be the case with an Island system, once batteries have been fully charged.

This ensures that your Solartech West Coast PV Grid-Tied system always operates at maximum capacity, yielding the lowest possible cost of generating green power per Kw/H. Also, as result of this and the lack of battery storage, Solartech West Coast PV Grid-Tied systems have the shortest payback periods. As these systems do not require any batteries, the required maintenance efforts are virtually negligible.

Grid-Tied systems do not offer backup in case of grid failure. Grid systems can be expanded to multi-hybrid systems at a later stage.

Advantages

Cost effective (short payback)

Simple

Staged, modular expansion

Easy installation

Compact

Reduced carbon footprint

Grid parity today

No serious lifestyle changes

No power storage losses

Low maintenance

High efficiency

Multi Hybrid

This system consists of two alternative energy systems working together. An island system secures backup power to the "essential" appliances. A Grid-connected systems feeds power to both the essential and non-essential appliances. The topology of a multi hybrid system allows it to function as a full island system under grid-failure, ensuring an unlimited power supply to all essentials. As the grid=connected PV system is usually sized to serve both essential and non-essential appliances, it is well oversized in case of grid failure to supply the essential appliances. As the batteries will only cycle in case of grid failure, standby batteries can be used that achieve similar life to that of cyclic batteries but are far more cost effective. Battery backup is then only sized for essential appliances and therefore significantly less than typical off-grid applications.

Advantages:

Reliable supply for essential appliances

Batteries will not be cycling if grid power is available

Battery backup is only for essential equipment resulting in a reduced battery bank

Standby batteries in this application can achieve similar life to cyclic batteries in a cycle application

Expandable in both the island and grid capacities

Surplus power is fed back into the grid and not dissipated as in island systems

Essential appliances can be selected and added

Disadvantages:

Only partial grid-independence is achieved

Smart Grid

Unlike typical grid connected PV systems that feed power into an electrical grid and may feed excess power back to utilities, smart grid systems are designed for optimizing self-consumption without any grid feedback. This process is achieved by obtaining daily weather forecasts and shifting manageable loads to matching generation times. In addition to load management, this system has the ability to throttle back the inverter's generation to prevent feedback of excess power to the national grid. These systems have online monitoring capabilities but do require a dedicated internet connection point, for daily weather forecasts as well as reporting.

As these systems do not require any batteries, the required maintenance efforts are negligible. Solartech West Coast Smart Grid PV Systems do not offer backup in case of grid failure. Solartech West Coast Grid Systems can be expended to Hub2 Hydrid systems at a later stage.

Advantages:

Cost effective (short payback)

Simple

Staged, modular expansion

Easy installation

Compact

Reduced carbon footprint

Grid parity today

No serious lifestyle changes

Low maintenance

High efficiencies

Island Farm House

Energy generated from the PV modules is used by inverters to produce 220Vac power. Surplus power is stored in batteries to ensure power availability when usage exceeds PV production. Battery storage is sized in order to achieve about 3 days autonomy. As the batteries will be working on a daily basis, cyclic batteries should ideally be used. The Victron Multi and Quattro island systems are true hybrid inverters. True hybrid inverters have the ability to select how it will interact with the grid supply. If grid supply is in the form of national grid, a true hybrid inverter can be programmed to ignore the dedicated supply and only accept due to low battery or load exceeding inverter specification. In the case of generator supply it can manage the generator and be programmed not to overdraw the generator. True hybrid inverters are expandable in parallel or three phase.

Advantages:

Grid independance

Expandable into parellel or three phase

Reliable power supply with grid/generator backup

Disadvantages:

Batteries will be cycling on a daily basis

Once battery capacity is reached, power generated by the PV system is dissipated.

Battery capacity needs to ensure autonomy for about 3 days

Hub2 Hybrid

Hub2 Hybrid systems are used for maximizing self-consumption with a grid presence. This system combines weather prediction, load optimization & feedback unique to Smart Grid Systems with surplus energy recovery of the hub2 island system. This system will run a residence "off-grid" or on "1A power assist" during the night, discharging the batteries to a predetermimd level. Once the predetermined state of charge is reached the island inverter will go back to full grid support, but instead of charging the batteries, will wait for "surplus" power the following day before the batteries are charged up.

Unlike Grid-Tied systems the Hub2 Hybrid system autonomously switches to island operation in cases of grid power failure, which means that your green power will be available during outages. The cyclic batteries will give you up to 15 years of suplus recovery while enjoying the benefits of backup for essential appliances.

Your Advantages

Staged, modular expension

High efficiencies

Batteries allow for surplus energy recovery

Batteries are of cyclic type, with up to 15 year expected life

Feedback prevention

Flexible load shifting

Option of external power source )grid, generator, wind)

Backup

Backup systems are solar ready, and can easily be integrated to a multi-hybrid system to ensure unlimited backup and cost saving when power is available. The battery autonomy is tailored for every client, and can easily be increased if required. All our backup systems have local monitoring with features like "State of Charge", "Time to Go", "Charge Emitted" and many useful functions that is essential if backup is important and have internet capabilities.

How the energy of the sun is converted into electricity

The question is – how does solar work and why solar at all?

The most important provider of energy to the earth is not coal as many of us are led to believe, but is the sun – furthermore, coal is the worst fuel for carbon emissions.

Everything living is dependent on the sun for its survival as it not only gives us light but it also offers warmth and is inexhaustible in addition to being renewable, plus there is so much of it that is so readily available, especially to the continent of Africa.

The amount of solar energy that the earth receives on a daily basis is far more than the total energy that we need – as a matter of fact – almost 6 000 times more. Southern Africa is swathed in a solar resource easily available and is perhaps the highest in the world enjoying sunshine almost all year round. The solar radiance levels, particularly those in the Northern Cape and the North-West Province, which means that the strength of the solar power received can be used over and over again.

Solar or photovoltaic cells are designed in such a manner as to capture as much of the sun’s rays as possible.

The daylight energy from the sun is converted into electricity.

A singular solar cell consists of two paper-thin plates that are made out of semi-conductive material such as silicon with a layer of chemicals on their surface.

The photons are converted into electrons.

When the sunlight falls on the cell, electrons are released from the silicon.

They then move over the layer of chemicals which generates an electric current.

This solar energy can be used to power most electrical appliances.

Although these were thought to be a costly method to produce electricity, price reductions in recent years have caused solar PV generated electricity to become more accessible to the ordinary man in the street.

Solar energy is already cheaper than using coal to produce energy.

If you are keen to cut back on your monthly electricity bill, solar is the way of the future.

Needless to say South Africa is well-placed to make use of this free and reliable source of energy which the sun has to offer.